You’re standing in your driveway looking up at your house. You’ve decided to go solar but have no idea how large a system your roof can support.
You’re also wondering what factors impact the efficiency of your solar system. You might ask yourself: Where should I put the panels? How does shading affect the productivity of the panels? How much roof space do I need? Does the roof material affect the solar installation?
Here are the five main factors that have an impact on the efficiency of any solar system.
1. The Location
The location of your property will have an impact on how much electricity your solar panels can generate.
The Orientation of Your House
Determining the orientation and tilt angle of your solar panels is one of the most important considerations in designing your solar system. In the southern hemisphere, north is usually the best orientation for panels. But not everyone has a perfectly oriented roof. So what other options do you have?
The Sun’s Movement Throughout The Day
During the course of a day, the sun passes through the sky in an arc (see image). The house on the image has a north-facing roof space. However, if your home does not have any north-facing roof space available, but does have two sides that face east and west, you may be asking yourself which side would be a better location for the most power generation.
Solar panels that face east will produce more electricity in the morning and less in the afternoon. They can suit households with high consumption in the morning, such as ones that use a lot of electric heating on cold winter mornings or people who are out of the house in the afternoon.
The production of panels facing north-east will be between that of north facing panels and east facing ones.
Panels facing west produce less electricity in the morning but more in the afternoon. West can be a good direction for people who use air-conditioning a lot during summer. It is also an excellent direction for people who are usually out of the house by the time the sun comes up but return in the afternoon.
The electricity production of solar panels through the day that face north-west will be between that of north and facing panels and that of west facing panels. They are slightly more efficient during the afternoon and slightly less in the morning.
East And West Orientation
Placing some solar panels facing east and some facing west is often called an east/west split and has the advantage of producing a more constant output of electricity during the day which can help to increase self consumption.
Another factor which has an impact on the efficiency of your solar power system is the geographic location of your house. Depending on your latitude, a different amount of energy will be available. Your location affects how perpendicular the sun is and how much atmosphere the sunlight needs to travel through to reach you.
Australia happens to have one of the best latitudes in the world for solar energy. If you’re thinking about getting solar energy in NSW, your latitude will be around 26 °.
The angle of the sun in the sky depends on both the season and your location on the earth. In winter the sun is lower in the sky, while in summer it is higher. So now you may ask yourself how to calculate the perfect tilt for your solar panels?
This is actually very simple: The ideal angle for your solar panels is simply the latitude of your location.
3. Roof Angle
Another factor that is connected to the perfect angle of your solar panels is the angle of your roof. Different roof angles affect the performance of your solar panels.
We can’t change the angle of your roof, but we have the option to include tilts in the mounting of your panels.
No matter what angle your current roof is, our Clean Energy Council Accredited Electricians will be able to calculate the best configuration to maximise your solar output. By maximising your output, we can ensure you get the best return on your investment.
4. Roof Shading
This is very important. Solar panels work best when there is no shade cast upon them. If your roof is covered in shade most of the day throughout the year, it might not have enough “solar window” to justify the costs of panels. Having a completely shaded roof will reduce the efficiency of your panels by over 60%.
Strategies for Dealing with Shading Issues
The performance and therefore your return on investment (ROI) from your solar power system can be affected by shading. Especially shading that occurs regularly due to an object that casts a shadow at the same time every day. However, there are a number of ways to avoid these effects.
Make sure that there are no nearby trees which might grow tall enough to eventually cause shading issues.
If the shading on your roof is not extensive, then micro-inverters or optimisers might be the right option for you. They get around the problem of partial shading by eliminating the need for strings in the first place.
Both micro-inverters and optimisers essentially allow every solar panel in a system to operate independently. That way, the overall energy production is not affected by one or two shaded panels.
If you want to find out more about the options you have, request a free energy assessment and we’ll connect you with a dedicated local solar specialist.
4. Roof Material
Sometimes the roof material will impact how efficient your system is. The roof material can have effect how easy it is to install the panels on your home, or where they can be installed. In general, solar panels can be installed on almost every form of roofing, but placement can differ.
However, certain roofing materials present unique installation challenges. The roof material determines how many solar panels it can support, as well as how long your installation will take.
Most residential roofs in Australia are constructed from tin or tile. Tin roofs are easy to install solar panels on, with regular baton screws used as anchor points for the installation of your solar panels. They are also easy to drill through, which is another added bonus.
Generally speaking, having a tin roof is the cheapest to install a solar system on. Tiled roofs are also suitable, as long as the tiles are not too old and fragile. Other materials such as clay tiles, metals and rubber are suitable and should not pose any issues.
Terracotta tile roofs are difficult for installing solar panels since they are extremely fragile and break easily. Decramastic roof sheets are renown for leaking and the result is water damage in the roof cavity and on the ceiling of homes. These types of roofs are extremely fragile and therefore cause difficulties for installing solar systems.
4. Roof Space
Last but not least, how much space you have on your roof determines the size and therefore the efficiency of your solar power system. Residential solar power systems can be as small or as large as you want or need.
There’s no one-size fits all, so each has to be custom designed and built. Large solar power systems, of course, produce the most electricity and allow you to save the most money. Yet, even if you can afford to install the largest system, you might be limited by the size of your roof.
Before you climb a ladder and start measuring, it is important to figure out how much solar power you actually need.
First, check your recent electricity bill to determine how much electricity in kilowatt-hours (kWh) you use. That will give you a good indication of which sized system you might want to install.
While you may want your solar power system to offset your entire energy usage, it might not be practical. Large solar systems are expensive to install even with the government rebate. Also, limited roof space can be a problem. If that turns out to be the case, you have to maximise the output from your solar panels by deciding which part of your roof receives the most sunlight.
If you want an accurate quote from a company you can trust, all you need to do is say g’day. We’ll take care of the rest.